Our previous studies found that zinc oxide (ZnO) particles induced expression of intercellular adhesion molecule-1 (ICAM-1) protein in vascular endothelial cells via NF-kappa B and that zinc ions dissolved from ZnO particles might play the major role in the process. This study aimed to determine if zinc ions could cause inflammatory responses in a human promonocytic leukemia cell line HL-CZ. Conditioned media from the zinc-treated HL-CZ cells induced ICAM-1 protein expression in human umbilical vein endothelial cells (HUVEC). Zinc treatment induced chemokine and inflammatory cytokine release from HL-CZ cells. Inhibition of NF kappa B activity by over-expression of I kappa B alpha. in HL-CZ cells did not block the conditioned medium-induced ICAM-1 protein expression in HUVEC cells. Zinc treatment induced activation of multiple immune response-related transcription factors in HL-CZ cells. These results clearly show that zinc ions induce chemokine and inflammatory cytokine release from human promonocytes, accompanied with activation of multiple immune response-related transcription factors. Our in vitro evidence in the zinc-induced inflammatory responses of vascular cells provides a critical linkage between zinc exposure and pathogenesis of those inflammatory vascular diseases. (C) 2011 Elsevier B.V. All rights reserved.